1. Field of the Invention
This invention relates to bridged metallocene compounds. More particularly, it relates to bridged dicyclopentadienide derivatives of Group IVb metals. It also relates to the use thereof in catalyst systems for the polymerization of olefins.
2. Description of the Prior Art
Metallocene catalysts suffer from a disadvantage in that the polyolefin product has small particle size and low bulk density. There is therefore a need in the art for a catalyst system that would retain advantages for metallocene catalyst systems but eliminate the above-mentioned disadvantage thereof.
Morphology improvements have generally been obtained by immobilizing the metallocene on an inorganic carrier or on an organic functionally active carrier, for the purpose of heterogenization.
U.S. Pat. Nos. 5,145,819 and 5,243,001 and EP-A-582195 disclose bridged metallocenes wherein alkoxy substituents can be attached directly to the bridge.
EP-A-608054 generically discloses bridged metallocenes wherein the bridge may have as substituent a 1-20 C hydrocarbyl containing oxygen, phosphorus, nitrogen or sulphur.